Syria put its jets under Russian protection, and the US risks all out war if there's another strike
"The Syrian Air Force is not in good shape. It's been worn down by years of combat plus some ... significant maintenance problems," Defense Secretary Jim Mattis told reporters at the Pentagon, CNN Notes.
But still, combined with the dozens of planes from his Russian backers, Syrian President Bashar al-Assad has a completely asymmetrical air advantage over his adversaries - rebel groups that have little more than a few anti-aircraft missile launchers.
The move to bases near Russian missile defenses provides Syria with a clear deterrent against further US strikes. Experts say Russia's S-300 and S-400 anti-air defenses can knock down Tomahawk cruise missiles, which were used in the April 7 strike.
Additionally, Russia has moved three warships to Syria's coast, further complicating the US's options should it launch another strike.
US officials have repeatedly stressed that they are "prepared to do more" against Assad should more evidence of chemical weapons use appear in Syria, but the recent developments on the battlefield mean the engagement would be much more dangerous.
Dr. Igor Sutyagin of the Royal United Services Institute, an expert on Russian missile defense systems and strategic armaments, told Business Insider that the presence of Russian defenses doesn't guarantee the safety of Syria's planes.
"One air defense battalion with an S-300 has 32 missiles. They will fire these against 16 targets (maybe against cruise missiles they would fire a one-to-one ratio) but to prevent the target from evading you always launch two... but what if there are 50 targets?" said Sutyagin.
To further avoid detection, the US could use stealth aircraft like F-22s currently stationed in the theater.
Although the US could still carry out an attack against Syrian and Russian military targets, it would run a huge risk of killing Russian servicemen. During the April 7 strike on Sharyat airbase, the US warned Moscow ahead of the strike.
In this situation, when the target is Russian air defenses or planes on Russian bases, it's entirely unclear if the Russians would back away from their hardware, and killing Russian servicemen runs the risk of massive escalation.